1. Field of the Invention
The present invention relates to a horizontally polarized wave antenna, and more particularly, to a horizontally polarized wave antenna using a serial-feed mode, which produces a horizontally polarized wave by composing vectors of currents while using an existing serial arrangement mode.
2. Description of the Prior Art
A radar system mounted on a vehicle or the like involves a technology for implementing Intelligent Transportation Systems (ITS), and is a vehicle safe driving system that has been developed in order to prevent, in advance, an accident that may occur due to severe weather conditions or a driver's carelessness by sensing other vehicles or objects.
Such a vehicle radar system separately uses a preferred polarized wave as needed, among various polarized waves having different angles (e.g., a vertically polarized wave, a horizontally polarized wave, a circularly polarized wave, and a 45 degree polarized wave) in order to maximize a radar performance when sensing a reflector. For example, when many vertical structures exist, a horizontally polarized wave antenna is used. When many horizontal structures exist, a vertically polarized wave antenna is used. When weathers may affect, a circularly polarized wave antenna is used. Further, when a middle performance between vertical and horizontal performances is desired, a 45 degree polarized wave antenna is used.
Meanwhile, when a radar system is mounted on a vehicle, a portion for mounting the radar system is limited by various structures, such as an ultrasonic sensor within a bumper, a number plate, a fog lamp, and a support structure, there is no alternative but to limit the size of the radar system. However, in order to have a spatial resolution within a small detection angle, a planar antenna requires a transmission line having a long height component and a radiating element having a wide area so that the entire size of the radar system is enlarged.
Accordingly, the present embodiment represents a horizontally polarized wave antenna that is capable of realizing a horizontal directionality with a high resolution while keeping the entire size of the radar system small.